The reactivity of an atom arises from

(A) the average distance of the outermost electron shell from the nucleus.

(B) the existence of unpaired electrons in the valence shell.

(C) the sum of the potential energies of all the electron shells.

(D) the potential energy of the valence shell.

Outermost electrons are the electrons that are present in the outermost orbit of the atom. The reactivity is not determined by the average distance or mean distance between the outermost electron and center.

Thus, the reactivity of the atom does not arise due to the average distance.

Therefore, the given statement is false.

The tendency of the chemical elements that can either gain or lose electrons is referred to as reactivity. Unpaired electrons are the electrons that exist without a pair in the valence orbit or outermost orbit. If the electrons are paired in orbit, then it will not tend to attract the other electrons.

The presence of unpaired electrons is the reason for the reactivity of an atom. This electron tends to attract the electron from the other atom, which in turn increases the reactivity.

Therefore, the given statement is true.

Energy is the form that can be created and is transferred from one form to the other. There are two types of energy. It includes potential energy and kinetic energy. The electron tends to possess potential energy, which does not affect the reactivity of the atom.

Thus, the potential energy in the electron shells does not influence reactivity.

Therefore, the given statement is false.

The valence shell is the outermost shell present in the atom that holds the valence electrons, with a definite amount of potential energy. It is aform of static energy.

Thus, the valence shell is not an influencing factor for the reactivity of the atom.

Therefore, the given statement is false.